Blind rivet setting attachment for power tools

ABSTRACT

A reciprocable blind rivet setting head is automatically coupled to and uncoupled from a continuously circulating drive lug by means of a swingable coupling bar to provide for a slow rivet pulling stroke of the head in one direction and for a fast return stroke under spring pressure in the opposite direction. Without stopping circulation of the drive lug, reciprocation of the setting head may be stopped by swinging the coupling bar out of reach of the drive lug.

United States Patent 1191 11 3,822,595 Elflein 1 July 9, 1 974 BLIND RIVET SETTING ATTACHMENT 3,095,106 6/1963 Morrison 72/391 FOR POWER TOOLS 3,127,045 3/1964 Tschantz 72/391 3,244,241 4/1966 Ferwerda 173/119 Inventor: M ed em, Bad 3,321,033 5/1967 Benuska et a1. 173/119 Neustadt/Saale, Germany 3,359,777 12/1967 Lee 72/391 [731 AS99199 Wen-9nd Mewnwarenfabrik $231333 2/1323 131153;.......................1311: 35/531 Alfred Honsel, Frondenberg/Ruhr, Germany FOREIGN PATENTS OR APPLICATIONS 1,163,238 4/1968 Great Britain [22] 1972 1,292,113 4/1969 Germany [21] Appl. No.: 283,065

2 Primary ExaminerCharles W. Lanham Assistant Examiner-James R. Duzan [30] Forelgn Apphcatlon Pmmty Data Attorney, Agent, or FirmJames E. Nilles June 20, 1972 Germany 2230082 7 52 US c1 72/391'17 3/119 [57] ABSTRACT 521d 9/05 A reciprocable blind rivet setting head is automati- [58] Field of Search 72/391, 114, 454; 17'3/119 9 and ncwpled a I 1 circulating drive lug by means of a swingable couplmg 1 bar to provide for a slow rivet pulling stroke of the [56] References'cltgd head in one direction and for a fast return stroke UNITED STATES PATENTS under spring pressure in the opposite direction. With- 1,775,188 9/1930 Bowen 173/119 out stopping circulation of the drive lug, reciprocation of the setting head may be stopped by swinging the rown 1 1 2,965,258 12/1960 Wilson et a1 72/450 Coupling bar out of reach of the f' 3,082,898 3/1963 Bosch 72/391 2 Claims, 1 Drawing Figure BLIND RIVET SETTING ATTACHMENT FOR POWER TOOLS FIELD OF THE INVENTION The invention relates to the setting of blind rivets and it is concerned more particularly with the setting of blind rivets of the pull stem type which require a tool that will grip the stem portion of the rivet and apply a rivet clinching and stem severing pull thereto.

BACKGROUND OF THE INVENTION During the past, attachments for existing power driven equipment, particularly for portable electric drills, have been developed for setting pull stem type rivets. However, such attachments as heretofore constructed have not been entirely satisfactory from an engineering standpoint as well as from a performance standpoint. In one type of such blind rivet settingattachment as'heretofore known and as disclosed for in stance in US. Pat. No. 2,965,258, issued'Dec. 20, 1960 to R. O. Wilson et al., a reciprocable rivet setting head is moved during its return stroke at the same slow speed as during the work stroke so that the riveting operation is delayed in an uneconomical manner. Furthermore, in such earlier attachments the rivet setting head comes to rest in a random position upon disconnection of the drive power. Under these circumstances manipulation of the apparatus becomes difficult and requires skilled labor with correspondingly higher pay.

Further, in order to shorten the operating cycle of the rivet setting head attempts have been made to hasten its return stroke, but here again stopping of the rivet setting head occurred in random positions with consequent operational difficulties.

In another prior art mechanism for setting blind rivetsa mutilated gear drive has been used for reciprocating the setting head. This not only involved relatively high manufacturing costs but also undue wear of its operating parts. Moreover, this mechanism too had the disadvantage of random stops of the setting head upon disconnection of the driving power.

SUMMARY OF THE INVENTION Generally, it is an object of the present invention to provide an improved blind rivet setting tool which avoids the hereinbefore mentioned shortcomings and disadvantages of the prior art.

More specifically, it is an object of the invention to provide an improved'blind rivet setting tool wherein a reciprocable rivet setting head and a continuously circulating drive lug are operatively interconnected by automatically engageable and disengageable coupling means which in their engaged condition transmit a power stroke to the setting headand in their disengaged condition release the latter for a return stroke to its starting position. In this connection the invention more particularly contemplates the provision of an actuating mechanism for the rivet setting head which affords a relatively slow rivet pulling stroke under power and an accelerated return stroke of the rivet head under spring pressure to its starting position.

A further object of the invention is to provide an improved blind rivet setting tool affording a predetermined rest position for the rivet setting head to which the head will automatically return after each power stroke.

A further object of the invention is to provide an improved rivet setting tool of the mentioned character wherein the rivet setting head may be placed into said rest position and application of driving power to the tool may be continued without causing movement of the rivet setting head out of its rest position.

A further object of the invention is to provide an improved rivet setting tool of the mentioned character wherein the rivet setting head may be releasably locked in its rest position and remain locked out while application of driving power to the tool is being continued.

A further object of the invention is to provide an improved blind rivet setting tool of the mentioned character involving relatively few and structurally simple component parts; which will function reliably and without undue wear under severe operating conditions; and which may be manufactured at relatively lower costs.

These and other objects and advantages will become apparent from the following description of a preferred embodiment of the invention, reference being had to the accompanying drawing whose single FIGURE shows a schematic sectional elevation of an apparatus embodying the invention.

DETAILED DESCRIPTION The blind rivet setting tool shown in the drawing is constructed in the form of an attachment for a portable electric drill shown in dotted lines and generally indicated by the reference letter 1. The tool comprises a housing 2; a reciprocable blind rivet setting head 3; a power input shaft 4, and a power transmitting mechanism receiving power from the shaft 4 and actuating the head 3.

The shaft 4 is rotatably mounted in the housing 2 and has a projecting end portion adapted for coupling to a conventional chuck la. The power transmitting mechanism between the shaft 4 and the head 3 comprises a worm gear drive formed by a worm4a on the shaft 4 and a gear wheel 5 in mesh with the-worm 4a. A cylindrical drivelug 5a is secured to the gear wheel 5 for rotation therewith and extends laterally therefrom at a radial distance from the axis of the gear wheel 5. Rotation of the gear wheel 5 will therefore cause circular movement of the drive lug 5a within the housing 2'.

The rivet setting head 3 conforms with conventional principles of construction and operation and is therefore believed to require no detailed description thereof. ln'accordance with the present invention, the head 3 is slidably mounted on the housing 2, for inward rivet pulling and outward return movement relative thereto transversely to the axis of the gear wheel 5. A leaf spring 7 within the housing is anchored at one end thereto and at its other end bears upon the head 3 so as to bias it for return movement in outward direction relative to the housing. Driving power for an inward stroke is transmitted to the head 3 by means of a coupling bar 6 which is pivotally connected with in the housing 2 to the inner end of the head 3, and which has a recessed end portion 6a which is movable into and out of cooperative engagement with the drive lug 5a during rotation of the gear wheel 5 in the direction of the indicated arrow so as to successively pull the head 3 inward for a slow rivet setting stroke and to release it for a fast return stroke by the spring 7.

A double armed control lever assembly for the coupling bar 6 is pivoted on the housing and comprises an inner arm 8 therein and an outer manually operable actuating arm 9, the inner arm being engageable with the coupling bar 6 by manual torque applied to the outer arm so as to move the recessed end portion 6a of the coupling bar out of reach of the drive lug 5a.

The coupling bar 6 further has a recessed intermediate portion 6!) for releasable interlocking engagement with the distal end of the inner arm 8 of the control lever assembly whereby the coupling bar may be retained in a rest position out of reach of the drive lug 5a, such rest position being the diverted position of the coupling bar 6 which is indicated in dashed lines in the drawing.

A leaf spring is anchored at one end within the housing 2 and bears at its other end against the control lever arm 8 so as to bias the control lever assembly for swinging movement of its inner arm 8 into engagement with thecoupling bar 6.

Another leaf spring 11 within the housing 2 is anchored thereto at one end and bears at its other end against the coupling bar 6 so as to bias the latter for swinging movement into the path of circular movement of the drive lug 5a.

I The springs 10 and 11 are relatively proportioned so that the action of the spring 10 through the lever arms 8 upon the coupling bar 5 overcomes the action of the spring 11 upon the coupling bar in the opposite direction.

In orderto operate the tool, driving power may be applied to the shaft 4 while the coupling bar is retained 'in its rest position by interlocking engagement thereof with the control lever arm 8, such interlocking engagement being effected by adjustment of the outer arm 9 to the dotted line position shown in the drawing. After the rivet setting head 3 has been placed into operating position upon a blind rivet, the outer arm 9 of the control lever assembly may be moved manually in opposition to the spring 10 from the dotted line position to the full line position shown in the drawing. The spring 11 will thereby be enabled to swing the coupling bar 6 into the path of circular movement of the drive lug 5a. The drve lug 50 will then move into cooperative engagement with the abutment afforded by the recessed end portion 6a of the coupling bar. Continued rotation of the gear wheel 5 in the direction indicated by the arrow thereon will cause a slow inward, rivet clinching power stroke of the head 3. When the coupling bar reaches the position in which it is shown in dash-dotted lines in the drawing, the drive lug 5a detaches itself from the recessed portion of the coupling bar, and under the action of the spring 7 the rivet setting head 3 will then rapidly return to the starting position in which it is shown in the drawing.

Return adjustment of the control arm 9 from the full line to the dotted line position in the drawing will place the coupling bar into its predetermined rest position and keep it there while the tool remains attached to the drill 1 and the shaft 4 is continuously rotated by the latter.

The accelerated return stroke of the head 3 shortens the operating cycle of the tool; the automatic return of the head to its predetermined rest position after a power stroke facilitates operation of the tool by a relatively unskilled operator; and the compact overall design of the tool permits its use in close quarters.

I claim:

l. A blind rivet setting tool comprising a housing; a power input shaft rotatably mounted in said housing; a worm gear drive within said housing comprising a worm element connected with said input shaft and a gear wheel in mesh with said worm element; a drive lug secured to said gear wheel for rotation therewith and extending laterally therefrom at a radial distance from the axis of said gear wheel; a rivet setting head slidably mounted in said housing for inward rivet pulling and outward return movement relative thereto transversely to the axis of said gear wheel; resetting spring means biasing said head for said return movement; a coupling bar within said housing pivotally connected with said head and having a recessed abutment movable into and out of the circular path of movement of said drive lug by back and forth swinging movement of said coupling bar about its pivot connection with said head; auxiliary spring means biasing said coupling bar for swinging movement of said abutment into said circular path of movement of said drive lug, whereby said abutment will be engaged by said drive lug and said rivet setting head will be pulled inward for a slow rivet setting stroke by partial rotation of said drive lug in one direction and whereby upon continued rotation of said drive lug in said direction said coupling bar will be released from said drive lug for a fast return stroke of said rivet setting head by said resetting spring means; and releasable lock-out means for said coupling bar operable to retain the latter in a rest position which places said abutment outside said circular path of movement of said drive lug.

2. A blind rivet setting tool as set forth in claim 1, wherein said lock-out means comprise a manually operable lever pivoted on said housing and having an arm portion adapted to lockingly engage a shoulder on said coupling arm upon said outward return movement of said rivet setting head; and spring means biasing said lever into said locking engagement with said shoulder. 

1. A blind rivet setting tool comprising a housing; a power input shaft rotatably mounted in said housing; a worm gear drive within said housing comprising a worm element connected with said input shaft and a gear wheel in mesh with said worm element; a drive lug secured to said gear wheel for rotation therewith and extending laterally therefrom at a radial distance from the axis of said gear wheel; a rivet setting head slidably mounted in said housing for inward rivet pulling and outward return movement relative thereto transversely to the axis of said gear wheel; resetting spring means biasing said head for said return movement; a coupling bar within said housing pivotally connected with said head and havIng a recessed abutment movable into and out of the circular path of movement of said drive lug by back and forth swinging movement of said coupling bar about its pivot connection with said head; auxiliary spring means biasing said coupling bar for swinging movement of said abutment into said circular path of movement of said drive lug, whereby said abutment will be engaged by said drive lug and said rivet setting head will be pulled inward for a slow rivet setting stroke by partial rotation of said drive lug in one direction and whereby upon continued rotation of said drive lug in said direction said coupling bar will be released from said drive lug for a fast return stroke of said rivet setting head by said resetting spring means; and releasable lock-out means for said coupling bar operable to retain the latter in a rest position which places said abutment outside said circular path of movement of said drive lug.
 2. A blind rivet setting tool as set forth in claim 1, wherein said lock-out means comprise a manually operable lever pivoted on said housing and having an arm portion adapted to lockingly engage a shoulder on said coupling arm upon said outward return movement of said rivet setting head; and spring means biasing said lever into said locking engagement with said shoulder. 